But this was not easy, even for a doctor with unlimited experience in quinine. The smooth, tapering surfaces of the stalactites, standing on guard in long rows down one side of the corridor, glinted derisively as the explorers rushed past them frantically trying to curb the frenzy that had seized this perfectly harmless woman who was now leading them on to a goal that might have all kinds of disaster in store for them. As they drew nearer the end of the corridor, the expected opening that was to deliver them from their subterranean prison was not visible, at least to the hasty glance that could be spared from the absorbing pursuit of Mrs. Quayle. Nevertheless, the awkward rapidity with which they were hurrying on to their fate was to be rewarded, apparently, by the discovery of something that was different, at any rate, from the wilderness of rocks that hitherto had baffled them in this gloomy underworld--and it was not General Herran's mountain of gold and emeralds, either. Something made by man, and not by nature, was here. This was unmistakably revealed in an odd sort of structure towards which they were hurrying. At last they were confronted, they believed, by the clew to the mysterious beings who inhabited the place, whose presence had been indicated by the footprints, by the man in the toga, seen, or imagined, by Andrew, and vaguely suggested by the weird disappearance of the entrance to the tunnel through which they had hoped to make their escape. Here all these things that had filled them with alternate anxiety and curiosity were to be explained. Unfortunately, Mrs. Quayle's impatience to get on gave them no opportunity to reconnoitre, at a safe distance, the object they were approaching. Leighton especially, accustomed to the careful methods of science, would have preferred a more deliberate and cautious mode of travel to the brainless hurry into which his housekeeper had plunged them. As it was, the object looming before them, so far as they could snatch time to make it out, resembled a huge stone windlass. Even the cylindrical drum and the long curved handle hanging at the side of one of the tall uprights were of stone. Certainly, a windlass like this--if it was a windlass--had never been seen before. It could not be the work of modern times--it was much too clumsy for that. And of stone! Perhaps it belonged to the Stone Age. It was conceivable--and the notion stirred the depths of the savant's soul with delight--that here, in this subterranean chamber of the Andes, they were about to stumble upon an archæological find that would revolutionize the current theories as to primitive man and his development. But--was it a windlass? The two uprights carrying the long horizontal drum at the top, instead of in the middle, were some ten or fifteen feet high. With such an abnormal height, and such singular construction, the THING might be intended to serve as a gallows quite as reasonably as a windlass.